Logical Disk Device Names

Logical device names are used to access disk devices when you:

• Add a new disk to the system

• Move a disk from one system to another

• Access (or mount) a file system residing on a local disk

• Back up a local file system

Many administration commands take arguments that refer to a disk slice or file system.

Refer to a disk device by specifying the subdirectory to which it is symbolically linked (either /dev/dsk or /dev/rdsk), followed by a string identifying the particular controller, disk, and slice.

Specifying the Disk Subdirectory

Disk and file administration commands require the use of either a raw (or character) device interface, or a block device interface. The distinction is made by how data is read from the device.

Raw device interfaces transfer only small amounts of data at a time. Block device interfaces include a buffer from which large blocks of data are read at once.

Different commands require different interfaces.

• When a command requires the raw device interface, specify the /dev/rdsk subdirectory. (The "r" in rdsk stands for "raw.")

• When a command requires the block device interface, specify the /dev/dsk subdirectory.

• When you're not sure whether a command requires use of /dev/dsk or /dev/rdsk, check the man page for that command.

Table 20-1 shows which interface is required for a few commonly used disk and file system commands.

Table 20-1 Device Interface Type Required by Some Frequently Used Commands

Command	Interface Type	Example of Use
df(1M)	Block	df /dev/dsk/c0t3d0s6
fsck(1M)	Raw	fsck -p /dev/rdsk/c0t0d0s0
mount(1M)	Block	mount /dev/dsk/c1t0d0s7 /export/home
newfs(1M)	Raw	newfs /dev/rdsk/c0t0d1s1
prtvtoc(1M)	Raw	prtvtoc /dev/rdsk/c0t0d0s2

Specifying the Slice

The string you use to identify a specific slice on a specific disk depends on the controller type, either direct or bus-oriented. Table 20-2 describes the different types of direct or bus-oriented controllers on different platforms.

Table 20-2 Controller Types

Direct controllers	Bus-Oriented Controllers
Xylogics (SPARC)	SCSI (SPARC/x86)
IDE (x86)	IPI (SPARC)

The conventions for both types of controllers are explained in the following subsections.

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Note -

Controller numbers are assigned automatically at system initialization. The numbers are strictly logical and imply no direct mapping to physical controllers.

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SPARC: Disks With Direct Controllers

To specify a slice on a disk with a direct controller on a SPARC system, follow the naming convention shown in Figure 20-1.

Figure 20-1 Naming Convention for Disks With Direct Controllers on SPARC Systems

To indicate the whole disk, specify slice 2 (2).

If you have only one controller on your system, x will always be 0.

x86: Disks With Direct Controllers

To specify a slice on a disk with an IDE controller on an x86 system, follow the naming convention shown in Figure 20-2.

Figure 20-2 Naming Convention for Disks With IDE Controllers on x86 Systems

To indicate the entire Solaris fdisk partition, specify slice 2 (s2).

If you have only one controller on your system, w will always be 0.

SPARC: Disks With Bus-Oriented Controllers

To specify a slice on a disk with a bus-oriented controller (SCSI, for instance) on a SPARC system, follow the naming convention shown in Figure 20-3.

Figure 20-3 Naming Convention for Disks With Bus-Oriented Controllers on SPARC Systems

If you have only one controller on your system, w will always be 0.

For SCSI controllers, x is the target address as set by the switch on the back of the unit, and y is the logical unit number (LUN) of the drive attached to the target. If the disk has an embedded controller, y is usually 0.

To indicate the whole disk, specify slice 2 (s2).

x86: Disks With SCSI Controllers

To specify a slice on a disk with a SCSI controller on an x86 system, follow the naming convention shown in Figure 20-4.

Figure 20-4 Naming Convention for Disks With SCSI Controllers on x86 Systems

If you have only one controller on your system, v will always be 0.

For SCSI controllers, w is the target address as set by the switch on the back of the unit, and x is the logical unit number (LUN) of the drive attached to the target. If the disk has an embedded controller, x is usually 0.

To indicate the entire Solaris fdisk partition, specify slice 2 (s2).